When a composite device such as a Multi Function Peripheral (MFP) is used, a process to authenticate a user is performed. For example, when the user holds an IC card over the composite device, the composite device reads identification information about the user (hereafter “user identification information”) stored in the IC card, and the user identification information is transmitted to an externally disposed authentication server. The authentication server authenticates the user by comparing the user identification information transmitted by the composite device with information about the user (hereafter “user information”) managed by the authentication server, the user using the composite device.
Further, if authentication is successful, relevant user information about the user who has been successfully authenticated is obtained from the authentication server and cached in the composite device.
With respect to the composite device, there is a technique of speeding up an authentication process upon the use of the composite device by causing the composite device that the user may use to cache authentication information (see Patent Document 1, for example).